Monolithic piezoelectric transformer

Abstract

A monolithic piezoelectric transformer includes a piezoelectric substrate and input electrodes which include internal electrodes disposed in the piezoelectric substrate alternately and between piezoelectric ceramic layers and external electrodes provided on the corresponding upper and lower surfaces of the piezoelectric substrate. The length of the external electrodes is about 50% of an overall length L of the piezoelectric substrate. The length of the internal electrodes is longer than approximately 50% of the overall length L.

What is claimed is:  
     
       1. A monolithic piezoelectric transformer, comprising: 
       a piezoelectric substrate having a laminated body including a plurality of piezoelectric ceramic members, said piezoelectric substrate including a drive portion and a power generation portion which are arranged adjacent to each other in the longitudinal direction of said piezoelectric substrate;  
       said drive portion being polarized in the thickness direction of said piezoelectric substrate and including an input electrode, said input electrode including internal electrodes provided in said drive portion and external electrodes provided on a top and bottom surface of said drive portion such that said internal and external electrodes extend in the longitudinal direction of said piezoelectric substrate; and  
       said power generation portion being polarized in the longitudinal direction of said piezoelectric substrate and including an output electrode associated with said power generation;  
       wherein the length of the external electrodes in the longitudinal direction of the piezoelectric substrate is different from that of the internal electrodes and the length of said internal electrodes is about 55% to about 70% of the length of said piezoelectric substrate, and the lengths of said internal electrodes are substantially parallel to the lengths of said external electrodes.  
     
     
       2. The monolithic piezoelectric transformer according to claim  1 , wherein the length of the internal electrodes is greater than the length of the external electrodes and less than the length of the piezoelectric substrate. 
     
     
       3. The monolithic piezoelectric transformer according to claim  1 , wherein the length of the internal electrodes is at least about 50% of the length of said piezoelectric substrate. 
     
     
       4. The monolithic piezoelectric transformer according to claim  1 , wherein the internal electrodes are arranged in the piezoelectric substrate alternate and between the piezoelectric ceramic members. 
     
     
       5. The monolithic piezoelectric transformer according to claim  1 , wherein the internal electrodes extend from a longitudinal end of the piezoelectric substrate to a position located beyond a longitudinal center of the piezoelectric substrate. 
     
     
       6. The monolithic piezoelectric transformer according to claim  1 , wherein the length of the internal electrodes is about 60% of the length of said piezoelectric substrate. 
     
     
       7. The monolithic piezoelectric transformer according to claim  1 , wherein a portion of the piezoelectric substrate corresponding to a length of the internal electrodes functions as an effective drive portion. 
     
     
       8. The monolithic piezoelectric transformer according to claim  1 , wherein the length of the effective drive portion is greater than the length of the power generation portion. 
     
     
       9. A monolithic piezoelectric transformer, comprising: 
       a piezoelectric substrate having a laminated body including a plurality of piezoelectric ceramic member, said piezoelectric substrate including a drive portion and a power generation portion which are arranged adjacent to each other in the longitudinal direction of said piezoelectric substrate;  
       said drive portion being polarized in the the thickness direction of said piezoelectric substrate and including an input electrode, said input electrode including internal electrodes provided in said drive portion and external electrodes provided on a top and bottom surface of said drive portion such that said internal and external electrodes extend in the longitudinal direction of said piezoelectric substrate; and  
       said power generation portion being polarized in the longitudinal direction of said piezoelectric substrate and including an output electrodes associated with said power generation;  
       wherein a dimension of the external electrodes and a dimension of the internal electrodes are different from each other and the length of said internal electrodes is about 55% to about 70% of the length of said piezoelectric substrate, and the length of said internal electrodes are substantially parallel to the length of said external electrodes.  
     
     
       10. The monolithic piezoelectric transformer according to claim  9 , wherein the length of the internal electrodes is greater than the length of the external electrodes. 
     
     
       11. The monolithic piezoelectric transformer according to claim  9 , wherein the length of the internal electrodes is less than the length of the piezoelectric substrate. 
     
     
       12. The monolithic piezoelectric transformer according to claim  9 , wherein the length of the internal electrodes is at least about 50% of the length of said piezoelectric substrate. 
     
     
       13. The monolithic piezoelectric transformer according to claim  9 , wherein the internal electrodes are arranged in the piezoelectric substrate alternately and between the piezoelectric ceramic members. 
     
     
       14. The monolithic piezoelectric transformer according to claim  9 , wherein the internal electrodes extend from a longitudinal end of the piezoelectric substrate to a position located beyond a longitudinal center of the piezoelectric substrate. 
     
     
       15. The monolithic piezoelectric transformer according to claim  9 , wherein the length of the internal electrodes is about 60% of the length of said piezoelectric substrate. 
     
     
       16. The monolithic piezoelectric transformer according to claim  9 , wherein a portion of the piezoelectric substrate corresponding to a length of the internal electrodes functions as an effective drive portion. 
     
     
       17. The monolithic piezoelectric transformer according to claim  9 , wherein the length of the effective drive portion is greater than the length of the power generation portion.